: Replaced an almost new (~6 mo old)electric hot water heater (switching to nat gas). Could not get the last water out till I removed the drain cock. Then around a quart of this lumpy, whitish, soupy stuff poured out. It feels soapy. A day later, it is still lying on the ground in a small pile. What is this stuff? What should I do in the future to prevent this from forming in my new nat gas hot water heater? The "gunk" in your water heater was probably limestone or silt depending on what part of the country your in.It can seriously impact the effiency of your heater especially an electric because it attaches to the heating elements.Its not as bad in a gas heater but its still not good.All you have to do to eliminate this problem is drain it once or twice a year.Thi is very common and is not a problem.Good luck and always have fun with your projects! MikeStheplumber